The present invention relates generally to seats with adjustable back pads and seat pads, and is particularly concerned with an adjustment apparatus for adjusting the position of a seat pad and/or a back pad of a seat in order to accommodate users of various shapes and sizes.
Seats used in exercise machines, or as office chairs or the like, normally have adjustable seat pads and back pads so that the user can tailor the seat to accommodate their specific needs. Such adjustability is particularly useful for seats used in exercise machines for supporting a seated exerciser while performing exercises, because of the different sizes and shapes of the users and also because different seat and back pad positions may be preferable for performing different types of exercises. The adjustment device or apparatus must be convenient, durable, and safe, both in the office and in the health club environment, and in any other applications where an adjustable seat is required.
There are two major, known types of seat adjusters, those with fixed incremental settings and those without fixed increments (infinite adjusters). Adjusters without fixed increments provide infinite adjustments that allow the user to place the seat and back pads anywhere along the adjustment path. In theory, this type of adjuster should be preferable since the user does not have to locate a fixed setting when making an adjustment.
Three types of infinite adjusters are known in seats for exercise machines. The first type uses a threaded tension knob to apply pressure in order to hold the adjusting pad in place. The pad is mounted on one of two telescoping tubes. The user turns the knob to secure or release the pad-mounted tube. This is both easy to use and inexpensive, but has several disadvantages. First, the same adjustment must be made for movement in either direction. The threaded end of the adjustment knob mars the finish on the adjuster tube, and severe over-tightening can strip the threads and require replacement. If the knob loosens during use, the seat can slip, which could cause injury to the user. In commercial applications or health clubs, it is common for one user to over-tighten the knob so that it is difficult or impossible for subsequent users to loosen it. Additionally, adjustment locations cannot be easily documented and repeated. It is almost impossible for a user to place the seat in the same position every time. Because the adjustments are infinite and not fixed, the seat position cannot be accurately recorded. It is important when exercising to know your positioning on each piece of equipment. Full range of motion, amount of pre-stretch, and axis of rotation positioning are all determined by seat pad and back pad positioning. If the user is not in the proper position, they will not receive the full benefit from the exercise and could risk potential injury.
The second type of infinite adjuster uses leverage and the weight of the seat itself to secure the seat, by wedging it in place on the adjusting upright. The same type of adjustment is made for movement in either direction. In order to raise or lower the seat pad, user""s must lift the front end of the seat upward, releasing the weight of the seat. It can then slide up and down on the adjusting upright. One problem with this design is that, once tension is released, gravity and the weight of the seat can make it hard to control. The user must be paying attention and use both hands, or the seat could fall. If the front end of an unoccupied seat is accidentally bumped into, the seat could drop and damage the equipment or cause injury. This is a safety liability. This type of adjuster also has the problem of position identification and repeatability of a seat position.
The assisted adjuster is the third type of infinite adjustment mechanism. It utilizes a spring or gas shock to lift the seat automatically. While this works well in one direction, it requires the user""s body weight to apply force against the assisting device and move the seat in the opposite direction. Because of this, the user can only make adjustments when seated. This design is more expensive to produce and maintain or service. It also has the same problem as the first two types of infinite adjusters with position identification and repeatability. The same type of adjustment is required for movement in either direction.
Fixed incremental adjusters, while offering fewer adjustment positions, are more secure, and have the ability to accurately identify optimum seat positions for future use. These adjusters utilize a direct pinning system to lock the seat pad or back pad in place. There are generally four types of fixed adjuster.
The first type of fixed adjuster utilizes a straight through pin to lock two pieces of telescoping tubing together. A single through hole in the outer tube is lined up with one of a series of through holes in the inside tube, and the pin is inserted through both holes. This is a simple and effective way to lock the seat in place. Because the pad is secured in position, its position can easily be identified and repeated. The same procedure is used to adjust the pad in either direction. The disadvantage with this design is that the pin can work itself loose and back out. This will cause the seat to drop and can cause serious injury. Because the pin is not attached to the equipment, it is easily misplaced, making the equipment inoperable.
The second type of fixed adjuster uses a spring-loaded pull pin to replace the straight pin. In this design, a hole is drilled in the outer of two telescoping tubes and the pull pin xe2x80x9cbarrelxe2x80x9d is welded over it. A series of holes are provided in the inner tube. The pull pin, which is a spring-tensioned plunger with a knob on one end, is secured inside the barrel. The pull pin is pulled back against the spring, the inner telescoping tube is adjusted to the desired position, and the pull pin is released. The pad is then held securely in place and the spring tension prevents the pin from working loose. Misplacement of the pin is not a problem. The pad positioning is easily identified and repeated. One disadvantage to this type of fixed adjuster is that the user must use both hands to control the pad and pull the pull pin at the same time. This generally means that, when adjusting a seat or back pad, the user must get up from the seat in order to reach and control both the pad and the pull pin. This can be annoying, particularly when such an adjuster is used on multi-function exercise machines such as home gyms, which require constant adjusting of pads when switching from one exercise to another.
The third type of fixed adjuster is known as a twist and lift system. In this system, a round outer telescoping tube has a central channel machined along a portion of its length facing inwardly, with a series of spaced, downward angled slots running from one side of the channel. The round inner tube has a pin or bolt protruding outwardly and captured in the channel. The pin engages in one of the slots to lock the pad in a selected position. In order to adjust the pad position, the user must twist and lift the pad, which in turn twists and lifts the pin and slides it out of the slot and into the channel. From there, the pad can be adjusted up or down to the desired position, and twisted back down so that the pin engages in another slot. This is quick and simple, usually requiring only one hand, and the positions can easily be identified and repeated. The same procedure is used for adjustment in either direction. Because the system can only be used with round tubing, it is difficult and expensive to machine the channel and slots in the tube radius, and to position the pad square to the frame. Another disadvantage is the limited number of possible positions, and the increased distance between these positions as compared to other types of adjuster. A further disadvantage is that, if an unoccupied seat is accidentally bumped in a sideways direction, the pin may slide into the central channel, and the seat will then fall. Again, this could damage the frame of the machine or cause injury.
The fourth type of fixed adjuster is a ratcheting, lever system. It consists of a lever that is pivotally mounted to the outer telescoping tube and has a first end that protrudes through a hole in the outer tube to engage one of a series of holes in the inner telescoping tube. The lever is pivoted at a point between its first and second ends, and is designed to ratchet or automatically disengage from the inner tube when the pad is moved in a first direction, yet instantly pin the inner tube and secure the pad from movement in a second direction. When the pad is moved in the first direction, the following edge of an inner tube pinning hole engages the first end of the lever, forcing it to pivot out of the way and allowing the tube to adjust. The lever is weighted or tensioned so as to always remain in contact with the inner tube. This allows the first lever end to briefly engage each pinning hole as It passes, and to seat instantly into a pinning hole when the inner tube and pad stop. Because the lever is designed to pivot in one direction only, movement by the pad in a second direction wedges the leading edge of an inner tube pinning hole against the first or protruding end of the lever, securing the pad in place. To move the pad in the second direction, the lever is pivoted out of the hole by depressing its second end, disengaging the lever end from the inner tube and allowing the pad to be adjusted.
This ratcheting adjustment system combines the best features in other known adjusters. It has the ease and convenience of assisted adjusters. It can be adjusted with one hand (in one direction) like the twist and lift system, the pinning device is permanently attached, like the pull-pin system, and the pad position can be identified and repeated.
The ratcheting lever adjustment system also has several other advantages over other types of seat adjuster. First, the pad is designed to be adjusted by the user whether in or out of the exercise position. All fixed incremental adjusters allow the user to easily determine the number of position changes needed for proper pad placement. The user simply looks at the position marking and moves the pad accordingly. However, with a straight pin or pull pin, doing this is extremely difficult, if not impossible, from a seated position. The user would have to bend over to see the position marking when adjusting a seat pad, or twist around when adjusting the back pad, shift to take weight off the pad, pull the adjusting pin with one hand and the pad with the other hand, while simultaneously watching the position markings to make sure the proper position is achieved. Such a maneuver is difficult and uncomfortable to achieve. In contrast, with the ratcheting adjustment system, the lever always stays in contact with the adjusting inner tube, and the user can determine the number of position adjustments needed and count the number of xe2x80x9cclicksxe2x80x9d as the lever ratchets over each hole, without having to bend over or twist around to view the actual position markings.
Another advantage is ease of adjustment. Grasping and pulling a straight pin or pull pin, or squeezing a handle, can be difficult for users with a handicap, arthritis, or in rehab for a hand injury. With the ratchet system, the user can pull the pad when adjusting in one direction and then simply press down on the ratchet lever, using the knuckles, back, or heel of the hand or the wrist to adjust in the opposite direction. This eliminates the need to grip and pull a pin.
Existing ratcheting lever adjustment systems still have some disadvantages. In some known lever adjusters, the lever is mounted to pivot between two plates mounted on the outer telescoping tube. This is a safety liability because it creates a potential pinch area between the lever and each plate. The risk of pinching is compounded when the lever is spring-loaded to snap back into position when released. The lever is typically relatively short and narrow, providing limited contact area for the hands and potentially causing discomfort to the user.
It is an object of the present invention to provide a new and improved adjustment apparatus particularly suitable for adjusting the position of a seat pad or back pad of a seat or chair.
According to the present invention, an adjustment apparatus is provided which comprises an inner tube and an outer tube telescopically engaged over the inner tube, the inner tube having a series of spaced openings and the outer tube having a pinning opening for alignment with a selected one of the openings in the inner tube, a pivot bracket mounted on the outside of the outer tube at a location spaced a predetermined distance from the pinning opening, and a lever having a central portion pivotally secured over the pivot bracket and opposite first and second end portions projecting in opposite directions from the central portion, the lever having a transverse width greater than the width of the pivot bracket, the first end portion of the lever projecting over the pinning hole, a retaining pin projecting from the first end portion towards the pinning hole, and the lever being movable between an operative position in which the retaining pin extends through the pinning hole and an aligned hole in the inner tube to secure the tubes together, and a retracted position in which the retaining pin is spaced from the pinning hole, and a biasing device urging the lever towards the operative position, the second end portion of the lever comprising a handle portion for pressing by a user to release the inner tube from the outer tube to permit relative movement between the tubes.
The adjustment apparatus may be used for any application where adjustment of the position of a first member relative to a second member is desired, but is primarily intended for adjusting the position of a seat pad or back pad of a seat, for example a seat used on an exercise machine. In this case, one of the tubes is secured to a seat pad or back pad, while the other tube is secured to part of a fixed support frame for the seat or exercise machine. The same adjustment apparatus may be used for both the seat pad and back pad.
Since the lever is pivoted on top of the pivot bracket, rather than between two spaced pivot plates, and has a width greater than the width of the pivot bracket, it will completely cover the pivot bracket at all times and avoid possible pinch areas. The lever hides the pivot mounting system from view, and allows a user""s hand to comfortably make contact with the lever at any position without encountering any potential pinch area. The width of the lever is such that it can be operated by parts of the hand other than the fingers, for individuals having only limited use of their fingers.
In a preferred embodiment of the invention, the lever comprises a relatively broad, plate-like member having a flat central portion. The first end portion is angled upwardly from the central portion, and the second end portion is angled downwardly from the central portion at the same angle as the first end portion, so that the end portions are parallel to one another. The retaining pin extends perpendicular to the first end portion. The angles are such that, when the lever is in the operative position, the first end portion will be flat against the outer tube and the retaining pin will extend transversely through the aligned openings in the outer and inner tube, so that it makes full perpendicular contact with the pinning holes. This differs from prior art ratcheting lever adjusters, where the retaining pin extends at an angle through the pinning holes, creating a greater shear force and thus increasing the risk of shearing. The outer tube pinning hole in prior art arrangements often had to be an elongate slot rather than a circular hole, due to the angle of the retaining pin on entering the hole. This forces the inner tube pinning holes to be adjusted past their pinning or rest positions to allow the pin to engage them, and then to drop back to their pinning position. This produces free play or delay in both adjustment directions, and also may producing jamming between the inner tube pinning hole and lever, potentially producing an unsafe condition and making the lever difficult to retract. The arrangement of this invention avoids these problems because the retaining pin is designed to enter both pinning holes in a direction perpendicular to the holes, avoiding any free play in the pinning position.
Preferably, the central portion of the lever is longer than either of the end portions, and the second end portion may be longer than the first end portion to provide a greater area for contact by a user""s hands. The pivot bracket preferably comprises a pair of spaced parallel plates projecting outwardly from the outer tube, while the lever has a pair of downwardly projecting plates for engaging inside or outside the bracket plates, with a pivot pin extending through aligned openings in each of the plates. The biasing device preferably comprises a torsion spring mounted between the plates and acting against the second end portion of the lever so as to bias the first end portion towards the outer tube. Thus, both the pivot bracket and the biasing spring are hidden beneath the lever and risk of contact with or pinching of a user""s hand or fingers is substantially reduced or eliminated.